The "A36" designation is the material grade standard established by ASTM International. The "A" prefix indicates it is a ferrous metal specification, and the "36" historically denotes a minimum yield strength of 36 kilopounds per square inch (ksi), or approximately 250 Megapascals (MPa). This yield strength is the stress at which the steel begins to deform permanently and is the fundamental design property for structural members like H-beams.
There is no separate "A36H" grade. The "H" in common parlance (e.g., "A36 H-beam") refers solely to the product shape-the wide-flange or H-shaped cross-section-not a sub-category of the A36 chemistry. The correct specification is "ASTM A36 Structural Steel" rolled into a "W-shape" (Wide Flange) as defined by dimensional standards like ASTM A6. Therefore, "A36" defines the material's intrinsic properties, while "H-beam" describes its engineered geometry.